|
That still leaves the question: if the universe has a finite boundary, what is beyond that boundary?
Or are you saying that spacetime is a localized concept that has no meaning "outside" of our universe? (Not that there would be an "outside" in that case. Or a "before".)
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
|
|
|
|
|
Richard Deeming wrote: That still leaves the question: if the universe has a finite boundary, what is beyond that boundary?
This too is a point I was attempting to drive toward in a logical manner.
Though I freely admit my knowledge of any of this is very, very basic.
This was an idea too that at some point studying the physical mechanical universe becomes a study of metaphysical properties (when you reach the end of the physical).
|
|
|
|
|
raddevus wrote: All physical (non-philosophical conceptual) things have limits
Prove it.
|
|
|
|
|
raddevus wrote: The Universe, if physical -- and it is, must have a limit.
No.
|
|
|
|
|
PIEBALDconsult wrote: No.
The best and most rational argument in the entire conversation so far. 
To which I reply, with a most stunningly intelligent answer:
Yes, infinity +1! 
|
|
|
|
|
The universe could be infinite...
Or it could just loop on itself like a circle.. or the surface of a doughnut....
|
|
|
|
|
Super Lloyd wrote: or the surface of a doughnut....
So when we find the end of the universe the other side will be the counter of a bakery?
There are two kinds of people in the world: those who can extrapolate from incomplete data.
There are only 10 types of people in the world, those who understand binary and those who don't.
|
|
|
|
|
Imagine you are an ant on the surface of the doughnut.... What do you find at the end of the doughnut? where is the end? what is the sound of one handed man clapping?
|
|
|
|
|
Super Lloyd wrote: Imagine you are an ant on the surface of the doughnut.... What do you find at the end of the doughnut?
I see empty space above the doughnut. But perception does not change reality in this case.
There are two kinds of people in the world: those who can extrapolate from incomplete data.
There are only 10 types of people in the world, those who understand binary and those who don't.
|
|
|
|
|
Out of curiosity.. didn't you understand my explanation? or are you trolling?
I am really confused whether I need to explain or not...
|
|
|
|
|
Super Lloyd wrote: didn't you understand my explanation?
I guess not. You asked a bunch of questions so I don't see that as an explanation.
There are two kinds of people in the world: those who can extrapolate from incomplete data.
There are only 10 types of people in the world, those who understand binary and those who don't.
|
|
|
|
|
If you are a one dimensional being living on a circle like universe. The circle has no end, yet it is finished.
If you are a 2 dimensional being living on a sphere or a doughnut like universe, your universe has no end yet it is finished.
There is a good chance we live on some kind of hypersphere...
The question here were to make you think. It failed apparently.
To be exact not a 3D space floating in a 4D universe.... a 3D universe of its own with such properties as a 3D sphere in 4D universe...
modified 17-Jun-17 8:45am.
|
|
|
|
|
Super Lloyd wrote: It failed apparently.
Indeed.
There are two kinds of people in the world: those who can extrapolate from incomplete data.
There are only 10 types of people in the world, those who understand binary and those who don't.
|
|
|
|
|
Super Lloyd wrote: what is the sound of one handed man clapping?
Piece of cake[^]! 
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
|
|
|
|
|
Assuming that you're not trolling  ...
Just because something is not infinite does not mean that it isn't endless.
A loop is not infinite (inasmuchas it has a measurable size) but doesn't have an end either.
The Cosmos (and others) talked about this rather nicely with the 2D version of reality called Flatland. A Flatlander's reality could be mapped into our 3D reality by visualising it as inhabiting the surface of a sphere. The Flatlander walks and walks and soon finds themselves where they started. Seems infinite, but in fact is not.
If you map our 3D space into a higher dimensional reality (which would be difficult for us to imagine and really requires pure mathematics to explore) then we could travel in any direction and end up where we started, the implications of which would be very hard for our puny 3D brains to comprehend. The Universe seems intuitively infinite because otherwise we assume that there must be an "edge" but there probably isn't.
|
|
|
|
|
Ralph Little wrote: Assuming that you're not trolling
What is wrong with people on the internet. As soon as someone disagrees with you they must be trolling? 
Ralph Little wrote: A loop is not infinite (inasmuchas it has a measurable size) but doesn't have an end either.
I disagree. If you pick a point on the loop and call it the starting point, you can quickly see that there is also an endpoint.
There are two kinds of people in the world: those who can extrapolate from incomplete data.
There are only 10 types of people in the world, those who understand binary and those who don't.
|
|
|
|
|
> What is wrong with people on the internet. As soon as someone disagrees with you they must be trolling?
That was actually a joke. Don't take me too seriously. 
> I disagree. If you pick a point on the loop and call it the starting point, you can quickly see that there is also an endpoint.
In that case, you could arbitrarily call anything an "endpoint". I think what most people intuitively call an "end" in the context of this discussion, is somewhere you cannot go beyond, a point beyond which nothing exists. At least that's how I would interpret it.
Interestingly though, although people can conceive of an end of a universe as a concept, I don't know if they could actually describe what it would be like. Perhaps it would a big wall. Perhaps it would be just a void-like nothingness, but surely that would be just space with nothing in it and therefore not and end at all?
Sometimes trying to describe something precisely betrays our ignorance of what we actually mean.
|
|
|
|
|
Ralph Little wrote: you could arbitrarily call anything an "endpoint".
Yes. Because if you also pick an arbitrary starting point and then follow around the loop you'll end up at points you have already visited, thus you must have passed the end point.
Ralph Little wrote: but surely that would be just space with nothing in it and therefore not and end at all?
Precisely. Our brains cannot conceive, IMO, an end to space.
There are two kinds of people in the world: those who can extrapolate from incomplete data.
There are only 10 types of people in the world, those who understand binary and those who don't.
|
|
|
|
|
>Yes. Because if you also pick an arbitrary starting point and then follow around the loop you'll end up at points you have already visited, thus you must have passed the end point.
Sounds like we're only disagreeing on what the word "end" means then and whether or not you can go beyond it.
If, in travelling in any direction, you arrive where you started after some fixed time interval, then the Universe must be finite because you could measure the distance that you travelled and therefore determine the Universe's "size". It could be that there are physical reasons why this is impossible to do in practice analogous to moving faster than c. We do have good reasons for thinking that the Universe is expanding so measuring the size of the Universe might be difficult.
It might also be difficult to come up with a measurement unit to describe the size of the Universe since all measurements of anything are relative.
My 3 dimensional head hurts.
|
|
|
|
|
Ralph Little wrote: so measuring the size of the Universe might be difficult.
Might be.
There are two kinds of people in the world: those who can extrapolate from incomplete data.
There are only 10 types of people in the world, those who understand binary and those who don't.
|
|
|
|
|
You know I was just reading my last reply and it occurred to me that since there are no fixed points in space, how could you possibly determine when you had returned to your original position?
Blah.
|
|
|
|
|
Possibly not. In which case, what is beyond the edges of this non-infinite universe? More universes? If so, what demarcates the edges of this one and the edges of the others? Can they not all be part of a larger universe?
PS. My finite brain has just thrown a "Value out of range Exception"!
- I would love to change the world, but they won’t give me the source code.
|
|
|
|
|
Perhaps more realistically or at least more philosophically pleasing, a finite universe could still be unbounded, for example if it is a 3-ball or 3-torus or something like that. That would mean that you could travel an infinite amount in any direction and never find "the edge" (since there is no edge) but you may find yourself returning to a place you've been before. The volume would be finite that way, but you don't have to worry about how space itself can even have an edge at all and what that might look like.
But it isn't really known whether it's finite or not in the first place. It seems to be flat and isotropic, if it actually is flat and isotropic then it is infinite. But it might not be exactly flat, it might be curved less than could be measured so far. Or it might not be isotropic, or both.
|
|
|
|
|
My theory: The universe is like an expanding balloon with everything that currently exists sitting on the surface. Heavy objects like black holes, stars, and planets sink into the surface warping space-time to create gravity. If you could travel at a rate faster than expansion, you would eventually come back around to the starting point. The interior of the balloon is the past.
|
|
|
|
|
Maybe "space" is infinite, but the big-ball-of-wobbly-stuff we call "the Universe" isn't?
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
